1. Field of the Invention
The present invention relates to a hydroxygallium phthalocyanine crystal, an electrophotographic photosensitive member, a process cartridge, and an electrophotographic apparatus.
2. Description of the Related Art
At present, the oscillation wavelength of semiconductor lasers widely used as exposure devices for electrophotographic photosensitive members is long, 650 nm to 820 nm. Therefore, electrophotographic photosensitive members having high sensitivity to light with such a long wavelength are under development.
A phthalocyanine pigment is effective as a charge generation material with high sensitivity to light in such a long wavelength range and is used in a photosensitive layer of an electrophotographic photosensitive member. In particular, oxytitanium phthalocyanine and gallium phthalocyanine have excellent sensitivity properties. Various crystal forms thereof have been reported.
Particularly regarding hydroxygallium phthalocyanine, Japanese Patent Laid-Open Nos. 5-263007, 6-93203, and 10-67946 report various crystal forms. In particular, Japanese Patent Laid-Open No. 5-263007 describes that a hydroxygallium phthalocyanine crystal having strong diffraction peaks at Bragg angles 2θ±0.2° of 7.5°, 9.9°, 12.5°, 16.3°, 18.6°, 25.1°, and 28.3° as determined by X-ray diffraction with Cu Kα radiation has excellent sensitivity properties. Japanese Patent Laid-Open No. 10-67946 describes that a hydroxygallium phthalocyanine crystal having the strongest peak at a Bragg angle 2θ±0.2° of 28.1° as determined by X-ray diffraction with Cu Kα radiation has excellent sensitivity properties.